1. Field of the Invention
The invention relates to the catalytic polymerization of ethylene, alone, or with other .alpha.-olefin monomers.
2. Definitions
Various of the properties of the polymers discussed herein were determined by the following procedures or test methods:
Density: ASTM D-1505 -- Plaque is conditioned for 1 hour at 120.degree. C. to approach equilibrium crystallinity. PA1 Melt Index (MI): ASTM D-1238 -- Measured at 190.degree. C. reported as grams per 10 minutes. PA1 Flow Index (HLMI): ASTM D-1238 -- Measured at 10 times the weight used in the melt index test above. PA1 Flow Rate Ratio (FRR) = Flow Index/Melt Index
The flow rate ratio is a relative measure of the molecular weight distribution of a resin and is simply the ratio of the flow index value to the melt index value (440 psi melt index to the 44 psi melt index). This relationship between the flow rate ratio and molecular weight distribution is based on the phenomenon that polymers having a more narrow molecular weight distribution are more newtonian in melt flow behavior and thus have flows which are less sensitive to shear. Thus, polymers having a more narrow molecular weight distribution have a lower flow rate ratio.